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Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure,leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure,these cavities,called "bubbles" or "voids",collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble,but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal,causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers,and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior:inertial cavitation and non-inertial cavitation.
A propeller is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which,when rotated,exerts linear thrust upon a working fluid such as water or air. Propellers are used to pump fluid through a pipe or duct,or to create thrust to propel a boat through water or an aircraft through air. The blades are shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.
Supercavitation is the use of a cavitation bubble to reduce skin friction drag on a submerged object and enable high speeds. Applications include torpedoes and propellers,but in theory,the technique could be extended to an entire underwater vessel.
The Gibbs Brothers Medal is awarded by the U.S. National Academy of Sciences for "outstanding contributions in the field of naval architecture and marine engineering". It was established by a gift from William Francis Gibbs and Frederic Herbert Gibbs.
The Permit-class submarine was a class of nuclear-powered fast attack submarines in service with the United States Navy from the early 1960s until 1996. They were a significant improvement on the Skipjack class,with greatly improved sonar,diving depth,and silencing. They were the forerunners of all subsequent US Navy SSN designs. They served from the 1960s through to the early 1990s,when they were decommissioned due to age. They were followed by the Sturgeon and Los Angeles classes.
A ship model basin is a basin or tank used to carry out hydrodynamic tests with ship models,for the purpose of designing a new ship,or refining the design of a ship to improve the ship's performance at sea. It can also refer to the organization that owns and operates such a facility.
A propulsor is a mechanical device that gives propulsion. The word is commonly used in the marine vernacular,and implies a mechanical assembly that is more complicated than a propeller. The Kort nozzle,pump-jet and rim-driven thruster are examples.
The Voith Schneider Propeller (VSP) is a specialized marine propulsion system (MPS) manufactured by the Voith Group based on a cyclorotor design. It is highly maneuverable,being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries.
David Watson Taylor was a U.S. naval architect and an engineer of the United States Navy. He served during World War I as Chief Constructor of the Navy,and Chief of the Bureau of Construction and Repair. Taylor is best known as the man who constructed the first experimental towing tank ever built in the United States.
Alphonse Pénaud,was a 19th-century French pioneer of aviation design and engineering. He was the originator of the use of twisted rubber to power model aircraft,and his 1871 model airplane,which he called the Planophore,was the first aerodynamically stable flying model. He went on to design a full-sized aircraft with many advanced features,but was unable to get any support for the project,and eventually committed suicide in 1880,aged 30.
The Carderock Division of the Naval Surface Warfare Center is one of eight Naval Sea Systems Command (NAVSEA) Surface Warfare Centers. The headquarters is located in Carderock,Maryland with the historic David Taylor Model Basin. The division includes remote sites across the United States concentrating on engineering,testing and modelling ship and ship's systems for the Navy. It consists of approximately 3,200 scientists,engineers and support personnel working in more than 40 disciplines ranging from fundamental science to applied/in-service engineering.
Marine engineering is the engineering of boats,ships,submarines,and any other marine vessel. Here it is also taken to include the engineering of other ocean systems and structures –referred to in certain academic and professional circles as “ocean engineering.”
A water tunnel is an experimental facility used for testing the hydrodynamic behavior of submerged bodies in flowing water. It functions similar to a recirculating wind tunnel,but uses water as the working fluid,and related phenomena are investigated,such as measuring the forces on scale models of submarines or lift and drag on hydrofoils. Water tunnels are sometimes used in place of wind tunnels to perform measurements because techniques like particle image velocimetry (PIV) are easier to implement in water. For many cases as long as the Reynolds number is equivalent,the results are valid,whether a submerged water vehicle model is tested in air or an aerial vehicle is tested in water. For low Reynolds number flows,tunnels can be made to run oil instead of water. The advantage is that the increased viscosity will allow the flow to be a faster speed for a lower Reynolds number.
In marine engineering,a ship motion test is hydrodynamic test performed with ship models for the purpose of designing a new ship,or refining the design of a ship to improve its performance at sea. Tests are carried out in a ship model basin or "towing tank". There are various types of test:the model may be towed along a straight line or circular path,and may be subjected to oscillations. Forces acting on the vessel are measured using a dynamometer. The tests may be evaluating the overall design,or focusing on the characteristics of a propeller.
William Francis Gibbs was an American naval architect of the mid-twentieth century.
Hitoshi Narita is a Japanese naval architect,researcher,businessman,and an International Fellow of the Royal Academy of Engineering (FREng).
A ducted propeller,also known as a Kort nozzle,is a marine propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The Kort nozzle is a shrouded propeller assembly for marine propulsion. The cross-section of the shroud has the form of a foil,and the shroud can offer hydrodynamic advantages over bare propellers,under certain conditions.
Marshall P. Tulin was an American engineer working in hydrodynamics. He was the Director of the Ocean Engineering Laboratory,University of California,Santa Barbara. His pioneering work in the 1950s is credited with successful developments in the theory of supercavitation for naval engineering.
Frederick Henry Todd was a British naval architect,a member of the United States National Academy of Engineering,and a recipient of Gibbs Brothers Medal from the U.S. National Academy of Sciences.
Albert G. Mumma was a rear admiral in the United States Navy who played a pivotal role in the development of nuclear propulsion for warships. During World War II,he served in France and Germany with the Alsos Mission.
References
- ↑ "Dr. William B. Morgan | College of Engineering - The University of Iowa". engineering.uiowa.edu. Retrieved 2023-04-17.
- ↑ "Large Cavitation Channel (LCC)". 2007-08-07. Archived from the original on 2007-08-07. Retrieved 2023-04-17.
- ↑ "Wm. B. Morgan To Head Ship Performance Dept., Taylor Research". magazines.marinelink.com. Retrieved 2023-04-17.
- ↑ "Gibbs Brothers Medal". National Academy of Sciences. Archived from the original on 8 January 2011. Retrieved 13 February 2011.
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